This invention relates generally to testing apparatus for use with lasers and specifically to apparatus for the detection of laser beams that have penetrated a target.
Methods for laser beam penetration of a target currently include the use of thermopile infrared detectors which detect radiation reflected from a surface that is laser illuminated when burn through occurs, thermocouples affixed to the back surface of the target being burned through, and high speed movies. All of these systems fail to provide reliable high speed detection.
Thermopile infrared detectors operate at very low signal levels therefore requiring signal amplification and extensive shielding of signal leads from stray radiation. In addition the individual detectors are expensive and a large number of them are required to cover a substantial size surface area behind the target. In addition, infrared detectors are inherently temperature and vibration sensitive.
Thermocouples, like infrared detectors, operate at very low signal levels consequently requiring high electrical amplification and shielding from stray radiation. The single point coverage of the thermocouple requires the use of arrays of them to cover possible misalignment of a small beam on a large target.
High speed movies lack a simple interpretation scheme that allows the user to record events in chronological order. In addition all of these methods have difficulty in resolving events to under 10 milliseconds in time.